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HAWAIIAN ENGINEERING ASSOCIATION 

HONOLULU, T. H. 

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\ PRESS BULLETIN NO. 55 



Engineering Features 

OF THE 

WAIAHOLE WATER PROJECT 

OF THE 

Waiahole Water Co. 

Island of Oahu, Territory of Hawaii 


By Chas. H. Kluegel, Mem. Am. Soc. C.E. 

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HONOLULU 

JUNE, 1916 






























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WAR DEPARTMENT 

ARMY MAP SERVICE 

CORPS OF ENGINEERS, U. S. ARMY 




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6101 MACARTHUR BLVD 
WASHINGTON. D. C. 


LIBRARY 


ACCESSION NO : 


ACCES 


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Engineering Features 


of the 

Waiahole Water Project 


of the 

Waiahole Water Co. 

Island of Oahu, Territory of Hawaii 


By Chas. H. Kluegel, /Aem. Am. Soc. C.E. 


Honolulu 

The Hawaiian Gazette Co., Ltd. 
1916 







the main tunnel, Waiawa Gulch. 
















































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Engineering Features of the Waiahole Water 
Project of the Waiahole Water Company. 


ISLAND OF OAHU, TERRITORY OF HAWAII 
By Chas. H. Kluegel, Mem. Am. Soc. C.E. 

The general plan or scheme of development adopted was that 
recommended by Mr. J. B. Lippincott, C.E., who made an ex¬ 
haustive study of the project, going fully into the past histor> 
and study already made by Mr. J. Jorgensen and other parties, 
and reported to the Board of Directors of the Oahu Sugar Co., 
Ltd., under date of August 19, 1911. 

Mr. Lippincott was assisted in this work by Mr. W. A. Wall. 
During the following two years, the Waiahole Water Co., Ltd., 
was organized, and Mr. H. K. Bishop was appointed Chief En¬ 
gineer of the project in January, 1913, and the actual work of 
constructing the system began in February, 1913, the work being 
carried out directly by the Company under the direction of its 
Chief Engineer. 

This method of performing the work was followed until Octo¬ 
ber, 1913, when the remainder of the work, except the pipes 
across gulches, was let out to Mr. Jorgen Jorgensen, Contract 
Engineer. Mr. Bishop resigned as Chief Engineer at this time, 
and Mr. C. H. Kluegel was appointed Inspecting Engineer to 
complete the work. Later Mr. J. M. Young was appointed as 
Consulting Engineer. The work is thus divided into two stages. 

GENERAL PLAN 

The general plan provided for collecting the water from the 
many streams and gulches on the windward side of Oahu by 
means of tunnels through the ridges or spurs, and conveying the 
water, after collecting, through the mountain in the main tunnel 
to the leeward side of the Island, thence by tunnels, ditches and 
pipes, to the upper levels of Oahu Sugar Plantation. 

The tunnels connect up the various streams on the North side, 
and take in the water at the adits in the gulches. There are 27 
of these tunnels on the North side, varying in length from 280 
feet to 2332 feet, the aggregate length of the North side tunnels 
being 24,621 feet, or 4.66 miles, being in reality one continuous 



6 


tunnel. The number of adits at which water is taken in is 30, 
the intakes being located at the most advantageous points at the 
streams in the gulches. 

The maximum elevation at which water is taken into the tun¬ 
nel is 790 feet above sea level, and the grade or slope of the 
North side tunnels is 1.3 feet per thousand. 

The length of the main tunnel through the Koolau Ridge is 
14,567 feet, or 2.76 miles, the grade or slope being 2.0 feet per 
thousand. 

The elevation of the North portal of the main tunnel is 752 
feet above sea level, and at the South portal 724 feet. 

The length of the tunnels on the South side is 19,211 feet, or 
3% miles, this distance comprising 14 tunnels, varying in length- 
from 346 feet to 3329 feet. 

In these tunnels the slope or grade is somewhat less, being 1.3 
feet per thousand, thus delivering the water at the lower end of 
the South side tunnels at an elevation of 699 feet. From this 
point the water is conveyed by means of cement-lined open 
ditches, elevated concrete ditches, four steel pipes, and three red¬ 
wood pipes. It is delivered to the upper boundary of Oahu plan¬ 
tation at an elevation of 650 feet through several distributaries, 
and by the main ditch, which reaches this elevation at the boun¬ 
dary of Honouliuli. 

The water is also delivered into numerous reservoirs, especially 
at night, when irrigating the cane fields is inconvenient. One of 
the larger reservoirs, on the line of the Waikakalaua storm water 
ditch, has long been in use. It is called Five Finger Reservoir. 
Its elevation was a determining factor in establishing the grade 
elevation of the Waiahole conduit. 

The length of open ditch between the last tunnel and the Wai¬ 
kakalaua gulch is 20,000 feet, or 3.79 miles. This portion of the 
waterway crosses three gulches, where riveted steel pipes are 
used, ditches being impracticable. 

The first of these pipes is 78 inches in diameter, and 1125 feet 
long, the maximum head being 165 feet. The second pipe is 78 
inches in diameter, and 331 feet long, the maximum head being 
80 feet. The third pipe, at Kipapa Gulch, is 72 inches in diam¬ 
eter, and 2034 feet long, and the maximum head is 270 feet. The 
fourth pipe crosses Waikakalaua Gulch. It is 72 inches in diam¬ 
eter and 970 feet long, the maximum head being 220 feet. This 
pipe crosses two tracks of the Oahu Railway, passing over one 
track and under the other. The aggregate length of the four 
steel pipes is 4460 feet to the West side of Waikakalaua Gulch. 

The pipes are made of steel plates varying from %" thickness 
for the highest heads to yy r thickness for the upper sections. The 


7 


pipes are riveted together in five and one-third-foot sections. 
They are supported on concrete*"piers of varying heights, de¬ 
pending on the topography of the ground, and the spacing of the 
piers is, in general, about 26 feet, the spacing being chosen in 
multiples of section length. 

The intakes and outlets of these pipes consist of a heavy con¬ 
struction of concrete, reinforced, and the intakes are provided 
with iron grating bars to prevent the access of floating material 
of any kind, and as a safety precaution in case of a person or 
animal accidentally falling into the ditch near the pipe. 



72-inch steel pipe across Waikakalaua Gulch, looking west. 

The pipes are provided with blow-off valves at the lowest 
points, and with man-holes for inspection, cleaning and painting, 
it being recognized that to keep steel pipes of this kind in good 
condition requires careful and thorough painting at frequent in¬ 
tervals. 

Provision is. made by means of valves at the. lowest point of 
the Kipapa Gulch pipe to take out water for irrigating the lands 
in Kipapa Gulch, and other lands lying below that level, and also 
for power purposes, should this latter become desirable at some 





8 



72-inch steel pipe across bottom of Kipapa Gulch. 









9 


future time; the water from the tail-race of the power plant being 
then available for irrigation after delivering up its power, the 
available hydraulic head at this point, being 280 feet. 

West of Waikakalaua Gulch, through Hoaeae and to the upper 
boundary of Oahu Plantation in Honouliuli, the conduit consists 
of 12,650 feet of cement-lined ditches, and three redwood pipes 
5 feet in diameter, having an aggregate length of 2830 feet. 

SUBDIVISION OF WORK 

For convenience in administration, the project was subdivided 
as follows: 


North Division Tunnels. 

....24,621 ft. 4.66 miles 

Main Tunnel . 

....14,567 “ 2.76 

“ 

South Division Tunnels. 

....19,211 “ 3.64 

u 

South Division Ditch. 

....20,000 “ 3.79 

a 

Pipes . 

.... 7,290 “ 1.38 

a 

Hoaeae Ditch . 

....12,650 “ 2.40 

a 

Honouliuli Ditch. 

.... approx. 2. 

u 

Distributaries . 


u 

Total. 

.26.53 

miles 


not including extensions by Oahu Sugar Co. 

ORGANIZATION 

When the work was undertaken, the time of completion was 
considered an important element, and Mr. Bishop’s organization 
was planned to secure the most expeditious execution of the 
project. 

The office of the Chief Engineer was located in Honolulu, 
where all plans were drawn, all maps were made, and records 
kept. The purchasing of material and the accounting were also 
done at the main office. The force in this office consisted of an 
Assistant Engineer, whose work was chiefly on plans and in pre¬ 
paring designs under the direction of the Chief Engineer; 
draughtsmen, clerks, and stenographer. 

Reporting to the Chief Engineer were two Division Engineers 
—one located at each portal of the main tunnel, each Division 
Engineer having two parties in the field, each party consisting of 
a chief of party, transitman and rodman, and each division office 
had the services of a draughtsman for plotting up the notes and 
recording the data brought in by the field parties, all data being 












10 


sent in to the main office as soon as checked and worked up. 

Also reporting to the Chief Engineer was a General Superin¬ 
tendent of Construction, Mr. A. A. Wilson, who was in direct 
charge of all the constructing work. 

Reporting to the General Superintendent were two Assistant 
Superintendents, one located at each portal of the main tunnel, 
and each having in charge the tunnel foreman, the shift bosses, 
and the gangs of tunnel men. 

At the beginning of the tunnel work, three shifts of eight 
hours each were kept going. This was continued until the large 
amount of water coming into the tunnel, at North heading, 
became troublesome, and on account of the hardship on the men, 
working for eight hours in the cold water, it became necessary to 
cut the shifts down to six hours each, so that four shifts per day 
were employed for this heading. 

The temperature of the water in the tunnel was approximately 
66° F., or about 8° colder than the artesian water in Honolulu, 
or, roughly, about 1° for each 100 feet of elevation. 

Great care was exercised in checking the surveys, the triangu¬ 
lations and the levels. This was given special care on the main 
tunnel, it being realized that while a small error in alignment 
would be unimportant, it would be necessary that all levels be 
correct. This levelling was done in the field by three separate 
parties, each of which went over the line twice, checking his own 
work, and the results of all three parties were checked against 
each other and found to compare within very small limits, thus 
eliminating any possibility of error. The instruments used for 
this work were thoroughly adjusted and tested for accuracy. 

The work on the main tunnel was started at once after the 
surveys were checked and found correct, and was done at first 
by hand in order to save time and push the work along as far as 
possible pending the arrival and installation of the air drills and 
machinery. 

It was of importance that bases of supplies be established at 
each portal, so all possible speed was made in constructing the 
railway from Waikane landing to the North portal and the rail¬ 
way from Pump 6 at Oahu Plantation to the South portal. 

In the meantime, camps were established and sanitary conve¬ 
niences were built to comply with the requirements of the Board 
of Health. No serious sickness, such as typhoid fever, gave any 
trouble. 

With the above organization, the surveys were made and 
checked, the plans prepared, the transportation line, consisting of 
six miles of track leading to the South portal from Pump 6, and 
three and a quarter miles of railway from Waikane landing to 


11 


the North portal, was built; camps were built; work was laid out 
in the field; the power plants and machinery were installed, and 
the actual work of excavation and construction were well under 
way on October 1st, 1913, when this arrangement and organiza¬ 
tion was terminated. 



Gates at a section of finished conduit-. 

The actual amount of main tunnel then driven was 912 feet on 
the North side and 2050 feet on the South side, or about 20% of 
the length of the main tunnel was driven under the direction of 
Mr. Bishop. Some work was also done on the lateral tunnels on 
both sides, but this part of the work was not rushed so much as 
the work on the main tunnel, inasmuch as the time required for 
the latter was the governing factor which controlled the date of 
completion. 






12 


INTERFERENCE BY WATER 

While it was suspected at the outset that considerable water 
might be encountered in the main bore through the mountain, it 
was not anticipated at the beginning that enough water would be 
developed to materially interfere with the progress of the excava¬ 
tion. This hope was not realized, however, for the main bore 
had proceeded only about 200 feet from the North portal when 
water to the extent of two million gallons daily was developed— 
this on breaking through the first dyke. 

These dykes are hard, impervious strata of rock lying approxi¬ 
mately at an angle of 45° to the tunnel axis, and nearly vertical, 
and they occur at intervals of varying length. Between the 
dykes was the porous water-bearing rock, thoroughly saturated, 
and with the water pent up between the dykes often under con¬ 
siderable pressure, so that when a dyke was penetrated, the water 
would spout out from the drill holes and would gush forth from 
the openings blasted in the headings. As the work progressed, 
the water increased in quantity and the difficulty of the work 
was enormously greater on account of the water. 

The slope of the tunnel being downward from the North por¬ 
tal, the matter of getting rid of the water by drainage was also 
one of great difficulty. This at first was managed by lowering 
the floor at the North portal about 2 feet, this being thought suffi¬ 
cient at that time, and allowing the water to drain out by gravity. 

At about 900 feet from the North portal, the flow of water 
having increased to 26 million gallons daily, the floor was again 
lowered to five feet below grade at the portal, and at this stage 
the men in the heading were working waist-deep in cold water, 
in a perfect torrent, the inflowing water coming principally from 
the face and from the roof and sides for a distance back from 
the heading, the flow of water apparently following the heading 
fairly closely. The pressure of water in the drill holes inter¬ 
fered very much with the blasting, so that the ordinary methods 
of charging and firing could not be used. The final expedient 
resorted to to hold the dynamite in place until it could be fired 
was to pack the sticks of explosive in thin metal tubes of the 
diameter of a stick of powder, and of sufficient length to enclose 
the quantity of powder desired. This scheme gave good results, 
but was expensive and materially delayed progress. 

The texture and hardness of the rock varied considerably— 
some of it .being particularly soft and porous and much of it 
hard and flinty—particularly at the dykes. The dykes varied in 
thickness from 14 feet down to about 4 feet, but all the dykes 
were composed of very hard, close-grained rock which was ap- 


13 



% 


The Lord-Young Company’s wagon train hauling 72-inch pipe sections. 







14 


parently waterproof. All of the rock, however, was gritty and 
abrasive lava, and necessitated an unusual amount of drill sharp¬ 
ening, two of the latest type drilbsharpening machines being kept 
busy all the time. 

When the water had increased to the point where it could not 
be drained out by gravity by lowering the floor at the North 
portal, a siphon pipe made of redwood, and 16 inches in diam¬ 
eter, was installed, and this made it possible to drive the work 
ahead a short distance further. A second siphon pipe 20 inches 
in diameter was next installed at the side of the tunnel immedi¬ 
ately over the top of the 16-inch siphon, and this gave further 
relief and made it possible to extend the North heading to ap¬ 
proximately 1400 feet. At this point the maximum inflow of 
water was approximately 35 million gallons daily, which was 
taken out by the two siphons and gravity drainage. 

It was seen that the siphon method alone would not suffice 
for further drilling, so a relief or drainage tunnel was driven on 
the West side of and parallel to the main tunnel at a slightly 
higher level and on an ascending slope from the portal, its object 
being to intercept and drain off a portion of the troublesome in¬ 
flowing water. This tunnel was required to provide access at 
all times to the water register to be installed at the boundary 
between Waiahole and Waiawa, distant 1705 feet from the North 
portal. This expedient proved helpful after the tunnel was ex¬ 
tended in about 1400 feet. The two tunnels were then worked 
together alternately, first one and then the other, the floor of the 
main tunnel being kept above grade to avoid having the tunnel 
men work so deep in the water. They were working at this 
time in water about three feet deep. 

This alternate working was continued to 1700 feet from the 
North portal, where a chamber was blasted out of the solid rock 
on the side next to the relief tunnel. A cross-cut was made to 
connect the two, and a centrifugal pump of 13 million gallons 
capacity was installed, which raised the water of the main tunnel 
through a pipe to the relief tunnel, which, at this point, is some 
18 feet higher, and the relief tunnel acted as a drain. 

With this arrangement, the work proceeded until the two head¬ 
ings met on December 13, 1915, and although the trouble and 
difficulty with the water never entirely ceased, it was possible to 
proceed slowly at an average rate of about 12 feet per day of 
24 hours with three shifts. 

SOUTH HEADING, MAIN TUNNEL 

From the South portal the progress was rapid, often as high 
as 630 feet per month, or about 21 feet per day on an average, 


15 



Water issuing from Avater-bearing rock in the main tunnel, 10,550 feet from the South Portal. 
March 23, 1915. (The lanterns are held by men standing alongside a Loyner drill ) 






















16 


notwithstanding the long haul, which at the last was over two 
miles. 

The first dyke on the South side was struck at 10,518 feet 
from the portal, the first evidence of water being from the drill 
holes, from which the water spouted under pressure. 

The measurements of pressure by gage on some of the plugged 
drill holes showed a pressure of 65 pounds per square inch, cor¬ 
responding to a static head of 150 feet. When water was struck, 
the excavation was discontinued temporarily. The spouting drill 
holes were plugged, the track was removed, and the floor of the 
tunnel, which up to this point was mainly through porous rock, 
was lined with concrete with, a plastered cement surface; the 
walls in the meantime having been lined and cemented to make 
them watertight. Such portions of the tunnel as required over¬ 
head arching had been arched and made ready for use. 

The track was then replaced and the work continued at re¬ 
duced speed, due to the water, which came in in large quanti¬ 
ties, the maximum flow from this heading reaching 17 million 
galons daily, until the two headings met at 11,679 feet from the 
South portal. 

From the foregoing it will be seen that 80% of the length of 
the main tunnel was driven from the South portal, and 20% of 
the length was driven from the North portal, the difference in 
these proportions from the two headings being due to the pres¬ 
ence of water at a much earlier stage in the North heading. Had 
there been no water to contend with, the length driven from each 
heading would have been approximately the same. 

In order to give room for the water to flow from the heading, 
the track was raised on timbers of 4x12 in long lengths, placed 
edgewise as stringers, on top of which the track ties were laid. 
The track was 24" gage, laid with 16-pound and 20-pound T-rail. 
The cars used were the standard Koppel one-yard, all-steel dump 
cars. Electric locomotives driven by storage batteries were used 
in both headings. These gave good service on short hauls, 
except for the necessity of frequent recharging of the batteries, 
and minor difficulties due to water. 

A gasoline motor tractor was used for the long haul, until the 
track was raised in the South heading, the raising of the track 
leaving insufficient clearance for the gasoline locomotive. 

A cable haul was then installed, this operating entirely with¬ 
out interruption from the water and clearance. The steel cable 
used was one-half inch in diameter, and was approximately four 
miles in length, spliced to make a continuous cable, and running 
over a sheave secured to a timber in the floor of the tunnel at 
10,800 feet from the South portal. The cable tractor was a 


17 



Portion of tunnel, showing forms for arch of tunnel 
roof. 

double-drum puller with a cable tightener, and was driven by 
belt and gearing from a 50 H. P. electric motor. There was 
considerable wear on the cable, due to abrasion on the ties. This 
wear was much reduced by damming up the water in the tunnel 
at frequent intervals in order to permit the cable to run in the 
water, which, apparently, acted as a lubricant and reduced the 















18 


wear. The cable parted on two occasions, and delayed the work 
until a splice could be made. One cable was completely worn 
out and the second cable used was probably about half worn 
out, over a period of eight months. 

POWER PLANT 

At the outset it was planned by Mr. Bishop to supply electric 
power to the two portals for operating the air compressors and 
other machinery from a central power station, located at Pump 6, 
transmitting at high voltage by pole line to the two portals, the 
pole line extending past the South portal over the mountain to 
the North portal. 

This station was installed and the power line was built from 
Pump 6 as stated, but before it was completed, water had been 
struck on the North side, and the quantity was found to be suf¬ 
ficient to supply all the power needed, the available convenient 
hydraulic head being approximately 250 feet. The central steam- 
driven power plant was completed, however, and held at reserve 
for emergency use, although the plant and power line from Pump 
6 to the South portal was used very little. The central power plant 
consisted of 500 H. P. Babcock & Wilcox water-tube boilers, 
supplying steam at 180 lbs. pressure, to a 350 K.W. high-pressure 
non-condensing steam turbo generator set, delivering 3-phase 
current at 3300 volts pressure, stepped up and transmitted at 
11,000 volts to the two stations at the portals, and there stepped 
down to 250 volts for use at the motors. Oil fuel was used for 
the boilers, and the location at Pump 6 was chiefly on account of 
the convenience of fuel supply, which was drawn from the tanks 
supplying fuel to the boilers at Pump 6. 

The plant which actually supplied the power for use at the 
tunnel was a 350 H. P. Pelton water-wheel belted to 300 K.W. 
3-phase generator, these units being installed in the gulch below 
and near the North portal. 

There was an abundance of water from the North heading, and 
the head at the Pelton wheel was 250 feet. This made an inex¬ 
pensive and easily operated plant which was entirely satisfactory 
except at rare intervals when the water was low. The power 
was transmitted by pole line to the South portal in the opposite 
direction to that originally planned. 

The local plant at each portal contained a duplex 2-stage Inger- 
soll-Rand air compressor, supplying 800 cubic feet of free air per 
minute, at a pressure of 100 pounds per square inch, belted to 
electric motors; receivers; Leyner drills; sharpening machine; 
pumps; blacksmithing equipment; blowers for ventilation; a num- 


19 


ber of small machine tools for repair work, and facilities for 
making up the metal powder tubes. The air drills used were 
the water-Leyner drills up to 10 feet long. These drills use a 
jet of water under pressure which forces out the cuttings from 
the point of the drill. They are capable of rapid drilling, there 
being very little interruption from the clogging up of cuttings. 

Air was supplied to the drills by a 4-inch pipe line running to 
a manifold which was always near the heading. Each round 
required from 12 to 20 holes, eight to ten feet depth, the holes 
being drilled at slightly converging angles in order to break the 
rock effectively. Each round required from 50 to 100 pounds of 
40% or 60% dynamite, Giant brand being used. 



Steel pipes at Waikakalaua Gulch, crossing a branch of the 
Oahu Railway. The larger one is the new 72-inch pipe. 

The ventilation of the tunnel headings was secured by forcing 
air by means of blowers through 16-inch metal pipes which were 
carried along the side of the tunnel, the air being forced in con¬ 
tinuously. When a shot was fired, the direction of the blower 
was reversed for a while, and the smoke and foul air was drawn 






20 


out of the tunnel through the pipe until it was clear and fit for 
the men to work. This arrangement of ventilation proved ef¬ 
fective and saved a great deal of time. 

LABOR 

Special tribute should be paid to the Japanese tunnel men, 
without whom the excellent progress made on the tunnel would 
have been impossible. These “professional” tunnel men, as they 



Japanese professional tunnel men, Main Tunnel, July, 1914. 

call themselves, prefer this work to any other, and they appar¬ 
ently take delight in the hardships incident to the work, the 
exposure to the cold water, and the risk in handling explosives. 
They were on the job all the time and never failed to deliver the 
goods in situations in which white men or native Hawaiians 
would have been physically impossible. Most of the drilling and 
mucking was done by these tunnel men as sub-contractors—a 
bonus being given for rapid work, which sharpened their interest 
and never failed to give results. 

CAPACITY OF CONDUIT 

The size of tunnel section is approximately 7 feet wide and 7 
feet high, but in many places the section is larger, due to the 
uneven cleavage of the rock, and the fact that certain portions 
are unlined. The capacities of different portions of the conduit 
are as follows: 



21 


Tunnels 18-27 North side. 80 million gallons daily 


Tunnels 13-18 North side. . . . , 

.100 

do. 

Tunnels 1-13 North side._ 

.115 

do. 

Main tunnel .*. 

.150 

do. 

Lateral tunnels South side. . . ., 

.125 

do. 

Pipes and ditches to Kipapa Gulch. .. .125 

do. 

Pipe across Kipapa Gulch . . ., 
Ditches beyond Kipapa Gulch. 

.100 

do. 


140 and 40 

do. 

Pipes beyond Kipapa Gulch... 

. 100 and 40 

do. 



72-inch steel pipe, Kipapa Gulch. 


The capacities of the various parts of the conduit are affected 
to a considerable extent by the slope or grade. The tunnel sec¬ 
tion was governed to a very large degree by the minimum size in 
which the most rapid work could be done, and in general the 
section for this reason is greater than the 7-feet size specified. 

MEASUREMENT OF WATER 

The main bore through the mountain was intended at the 
beginning to be merely a conduit to convey the water from one 
side to the other, but in the process of building the tunnel, water 











22 








Location of water-measuring station between lateral tunnels H and I, Waiawa Gulch. 













23 


was developed so that this became a source of supply, and for 
this reason it is necessary to measure the flow at certain boun¬ 
daries as a basis of payment for the water to the owners of the 
land. Two stations for the measurement of water are operated, 
one at the boundary of Waiahole and Waiawa, and one between 
lateral tunnels H and I on the South side, measurements at these 
points being all that are required for payment of the water. 
These stations are in channels of uniform sections which are 
rated, and the stage of water is recorded by an automatic water- 
stage register, thus giving a permanent record of the daily flow 
as a basis for payment. 



Open ditch in Waiawa, with cement lining. 


The maximum quantity of water developed was on October 
16, 1914, and was approximately 35 million gallons daily from 
the North portal. The flow of water has varied considerably 
from time to time, and has been decreasing, apparently indicating 
that the water stored in the mountain between the dykes is grad¬ 
ually being drained off. It is thought that the permanent or con¬ 
tinual flow from the tunnel bore will be governed by the rainfall 
over this drainage area. The present flqw of water percolating 
into the main tunnel is 14 million gallons daily. This appears to 
be the dry weather flow. 

CLOSED CONDUIT SYSTEM 

This system of tunnels is essentially a closed-conduit system— 
that is, the flow is entirely through closed tunnels, not subject to 





24 


interruption by freshets or washouts or from rubbish or wash 
from the mountain streams, the intakes being so built as to admit 
only water as free from rubbish as practicable. Only at three 
points in the tunnel system—and these are on the South side, one 
of which is a gaging station—does the water flow in open chan¬ 
nels for an aggregate length of 160 feet. 

Pipes were not a part of the contract to Mr. Jorgen Jorgensen. 
Steel pipes were let out to contract to the Lord-Young Engineer¬ 
ing Co. The last of these pipes has just been completed. The 
contract for the redwood pipes was let to Lewers & Cooke, Ltd. 

It is intended to use the reservoirs so far as possible to take 
care of the water flowing at night, so as to utilize the conduit to 
its fullest capacity. 

The Waiahole Water Co. has taken over from the Oahu Sugar 
Co. the Ahrens Ditch in Waiawa, the Kipapa Ditch, the Wai- 
kakalaua Ditch in Waipio, and the Hoaeae Ditch. Two redwood 
pipes having total length of 1223 feet have been laid across two 
gulches on the line of Hoaeae Ditch, cutting out 2*4 miles of 
ditch. 

The water delivered by the Waiahole System is chiefly used 
on newly-planted cane on land above the lift of the pumps. 
During construction the water developed in the main tunnel near 
the South portal was at times utilized for irrigation. On May 
27, 1916, with Mr. H. Olstad as Superintendent, continuous oper¬ 
ation of the project was begun. 

































































































